Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Weighted-Average Assumptions Used to Value Stock Options

The weighted-average assumptions used to value these stock options using the Black-Scholes option-pricing model were as follows.

	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Fair value of common stock	$	1.28		$	38.14		$	1.49		$	37.89
Risk-free interest rate		3.06	%		1.03	%		2.25	%		0.96	%
Dividend yield		0.00	%		0.00	%		0.00	%		0.00	%
Expected term of options (years)		5.78			5.84			5.88			5.89
Volatility		71.45	%		69.70	%		68.57	%		69.80	%

Summary of Stock Option Activity

The table below summarizes the stock option activity during the six months ended June 30, 2022:

	Number of Shares Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Balances at December 31, 2021		1,281,396		$	18.18	7.94
Granted		1,149,166		$	1.49
Exercised		(1,098	)	$	1.06		$	-
Cancelled/Forfeited		(90,728	)	$	31.80
Balances at June 30, 2022		2,338,736		$	9.46	8.59	$	218
Vested and expected to vest at June 30, 2022		2,338,736		$	9.46	8.59	$	218
Exercisable at June 30, 2022		361,666		$	22.41	7.88	$	16

Summary of Restricted Stock Unit Award Transactions

Restricted stock unit awards outstanding as of June 30, 2022 were as follows:

			Weighted Avg
			Grant Date
	Shares		Fair Value
Outstanding at December 31, 2021		258,851	$	3.36
Granted		—		—
Forfeited/Cancelled		—		—
Issued as Common Stock		—		—
Outstanding at June 30, 2022		258,851	$	3.36

Summary of Stock-Based Compensation Expenses

Stock-based compensation expenses included in the Company’s condensed consolidated statements of operations for the three and six months ended June 30, 2022 and 2021 were (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	380	$	364	$	666	$	668
General and administrative		814		644		1,583		835
Total	$	1,194	$	1,008	$	2,249	$	1,503